Which of the following sets of quantum numbers is not possible for the electron?

The uncertainty in the position of electron $(\Delta x)$ is approximately 100 pm . The uncertainty in momentum (in $\mathrm{kg} \mathrm{ms}^{-1}$ ) of an electron $\left[h=6.626 \times 10^{-34} \mathrm{Js}\right]$

Which of the following statements are correct?

I. The energy of hydrogen atom in its ground state is -13.6 eV .

II. On the basis of Bohr's model, the radius of the 3rd orbit of hydrogen atom is 158.7 pm .

III. The order of radius of the first orbit of $\mathrm{H}, \mathrm{He}^{+}, \mathrm{Li}^{2+}$ and $\mathrm{Be}^{3+}$ is $\mathrm{H}>\mathrm{He}^{+}>\mathrm{Li}^{2+}>\mathrm{Be}^{3+}$.

When a metal surface is irradiated with light of frequency $x \mathrm{~Hz}$, the kinetic energy of emitted photoelectrons is $z \mathrm{~J}$. When the same metal is irradiated with light of frequency $y \mathrm{~Hz}$, the kinetic energy of emitted electrons is $z / 3 \mathrm{~J}$. What is threshold frequency (in Hz ) of metal?